Appendicolith revealed on CT in children with suspected appendicitis: How specific is it in the diagnosis of appendicitis?

OBJECTIVE, The purpose of this study was to determine the sensitivity, spec ificity, and positive and negative predictive values of a diagnosis of appe ndicitis when CT without enteric contrast material reveals an appendicolith in children with suspected appendicitis. MATERIALS AND METHODS. A retrospective review of children who underwent abd ominal CT for suspected appendicitis over a 25-month period was per-formed to identify patients with an appendicolith. An age-matched group of patient s examined for trauma served as controls. RESULTS. CT was performed in 104 children. Appendicitis was present in 60 ( 58%) of 104 children; 39 (65%) of 60 had an appendicolith. Appendicitis was not present in 44 (42%) of 104; six (14%) of 44 had an appendicolith. An a ppendicolith detected on CT had a sensitivity of 65% and a specificity of 8 6% for the radiologist diagnosing appendicitis. An appendicolith had a posi tive predictive value of 74% and a negative predictive value of 26%. Among the control population, two (3%) of 74 children had an appendicolith. This number was statistically significant compared with children in the study gr oup with an appendicolith and abdominal pain, but without appendicitis (p = 0.02), CONCLUSION. Although an appendicolith is significantly associated with appe ndicitis, the detection of an isolated appendicolith on CT is not sufficien tly specific to be the sole basis for the diagnosis of acute appendicitis.